Carbon Dot Nanomaterials with High Interfacial Activity for Unconventional Reservoir Development

Abstract

Carbon dot nanomaterials (<10 nm) exhibit superior application prospects as oil displacement materials for unconventional reservoir development. However, the limited oil−water and oil−solid interfacial activity of carbon dot nanomaterials restricts their broader application. In this study, carbon dot nanomaterials (CDs) are expeditiously prepared via a microwave-assisted synthesis method utilizing urea and citric acid as precursor compounds. OAB-modified active carbon dot nanomaterials (OCDs) are prepared by grafting oleic acid amidopropyl betaine (OAB) through hydrothermal reaction at 90 °C for 5 h using CDs as a carbon dot carrier. Stability experiments show that the plentiful hydrophilic groups present on the surface of the OCD augment electrostatic repulsion among them, thereby imparting dispersibility, temperature tolerance (90 °C), and salt resistance (2.6 × 10 4 mg/L). Additionally, OCDs demonstrate optimal effectiveness at a concentration of 0.5 wt %. At this concentration, OCDs can reduce the interfacial tension to 0.66 mN/m and achieve the underwater oil contact angle to 126°. Within 24 h, OCDs can strip 60.6% of the oil film. OCDs show the excellent ability to enhance oil−water and oil−solid interfacial activity. Meanwhile, OCD nanofluids can effectively form emulsions with crude oil and spontaneously demulsify within 2 h in a state. Core flooding tests demonstrate that OCD nanofluids, when compared with simulated formation water, reduce injection pressure by 46.3% and enhance oil recovery by 31.1%. This study offers a promising solution for the efficient development of unconventional reservoirs with carbon dot nanomaterials.

Enhanced Oil Recovery in Low-Permeability Reservoirs Utilizing Dispersions of Monodisperse Crumpled SiO2 Nanoparticle

“…With conventional oilfield reserves depleting, low-permeability oilfields have emerged as a vital future source of oil and gas resources . These reservoirs are characterized by low permeability, small pore-throat sizes, poor connectivity, and significant heterogeneity, resulting in high development costs, substantial challenges, and low operational efficiency . These issues severely hinder the efficient exploitation of oil resources.…”